Method for rapidly preparing imine covalent organic framework film and application of imine covalent organic framework film

Abstract

The invention belongs to the field of covalent organic framework separation membranes, and discloses a method for rapidly preparing an imine covalent organic framework membrane and application of the imine covalent organic framework membrane, the preparation method comprises the following steps: step 1, preparing an amorphous membrane; and 2, converting the amorphous film into the COF film. The preparation method provided by the invention can overcome the problems of low speed and high condition requirements in the traditional imine COF membrane preparation process, and has the characteristics of simple preparation method, few steps, high repeatability, easiness in amplification and the like. When the prepared COF membrane is applied to a nanofiltration process, accurate molecular separation and relatively high solvent permeability are realized, and a thought is provided for large-scale preparation and industrial application of the COF membrane.

Description

Technical Field

[0001] The present invention relates to a method for rapidly preparing an imine covalent organic framework membrane and its application, belonging to the field of covalent organic framework membranes. Background Art

[0002] Covalent organic framework (COF) materials are recognized as one of the candidates for a new generation of high-performance membrane materials due to their characteristics such as uniform pore size, strong stability, and strong controllability. Compared with traditional polymer membranes, they exhibit unique advantages. Their regular and uniform pore channels are expected to break through the trade-off effect between solvent permeability and solute selectivity. At the same time, the adjustable pore size has strong adaptability in the face of different application scenarios, and there have been application reports in aspects including water treatment, gas separation, and energy storage. Imine COF membranes have become the most studied COF membranes at present because of their relatively simple synthesis, rich monomers, and strong group controllability. Imine COF membranes have great application potential in the field of water treatment, especially in the fields of molecular separation and molecular / ion separation. However, the insoluble and infusible characteristics of imine COF lead to poor processability. Therefore, in recent years, the research focus of scientific researchers has mostly been on the preparation of imine COF membranes. Existing methods for preparing imine COF membranes include in-situ growth, interfacial polymerization (including solid-gas interfacial polymerization, liquid-liquid interfacial polymerization, and liquid-gas interfacial polymerization), layer-by-layer self-assembly, and disorder-to-order transformation, etc. However, the formation of the regular high-crystalline structure of imine COF membranes often requires a long time and relatively harsh growth conditions, which greatly limits the large-scale preparation of COF membranes.

[0003] The dynamic imine bond guided by dynamic imine chemistry is the guiding ideology for the preparation of imine COF. The reversibility of the imine bond ensures self-repair and self-correction during the preparation of imine COF, thus forming a thermodynamically stable framework structure under certain conditions. The preparation of imine COF membranes is similar to that of imine COF, but limited by the slow crystallization process and poor film-forming performance of COF, the preparation process of COF membranes is often complex and prone to defects, resulting in poor separation performance. Therefore, the rapid preparation of high-crystalline defect-free COF membranes is a great challenge. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the present invention provides a method for rapidly preparing an imine covalent organic framework membrane, and the specific technical solution is as follows:

[0005] A method for rapidly preparing an imine covalent organic framework membrane, comprising the following steps:

[0006] Step 1: Preparation of an amorphous membrane

[0007] 1.8 mmol of benzene-1,3,5-tricarbaldehyde and 8.6 mmol of aniline were dissolved in 10 mL of ethanol and reacted at 80 °C for 24 h to prepare the aldehyde monomer BTPA; the aldehyde monomer BTPA was ultrasonically dissolved in N,N-dimethylacetamide to prepare an aldehyde monomer solution, and the amine monomer p-phenylenediamine PDA and different amounts of polyethyleneimine PEI were ultrasonically dissolved in N,N-dimethylacetamide to prepare an amine monomer solution. Further, the aldehyde monomer solution and the amine monomer solution were mixed and ultrasonically homogenized and then left standing for several hours; the mixed monomer solution was cast onto the upper layer of a glass slide, and an amorphous film was obtained after solvent evaporation;

[0008] Step 2: Conversion of the amorphous film into a COF film

[0009] The amorphous film obtained in Step 1 was placed in a mixed solution of a solvent and a catalyst, and heat-treated at 65 °C for a certain period of time to obtain a COF-PEIa(b) film, where a represents the content of PEI and b represents the heat treatment time.

[0010] Furthermore, in Step 1, the molecular weight of PEI is one or several of 600, 800, 1800, 3000, 10000, 30000 or 50000.

[0011] Furthermore, in Step 1, the usage amount of PEI is 10 μL, 20 μL, 30 μL, 40 μL or 50 μL.

[0012] Furthermore, in Step 1, the time for solvent evaporation is controlled to be 1 h, 3 h, 6 h, 12 h or 24 h.

[0013] Furthermore, in Step 2, the volume ratio of the solvent and the catalyst used in the heat treatment process is 2:8, 4:6, 6:4 or 8:2.

[0014] Furthermore, in Step 2, the heat treatment time is 1 h, 3 h, 6 h, 12 h or 24 h.

[0015] Application of the covalent organic framework membrane prepared by the described method in molecular and / or molecular ion separation.

[0016] The preparation method of the present invention uses aniline-modified benzene-1,3,5-tricarbaldehyde as the aldehyde-based monomer in the preparation process of the COF membrane, p-phenylenediamine as the amino monomer, and polyethyleneimine is incorporated into the COF through imine bonds to improve the film-forming property and fill defects. An amorphous film is obtained by evaporating the solvent through a simple casting method, and a COF film is obtained by a hydrothermal process to achieve rapid crystallization. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the process flow for rapidly preparing a COF membrane;

[0018] Figure 2XRD patterns of the amorphous film and the COF film. Detailed implementation mode

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] Example 1

[0021] The method for rapidly preparing an imine covalent organic framework film of the present invention includes the following steps:

[0022] Step 1: Preparation of the amorphous film: Weigh 291.85 mg of phloroglucinol and 783.65 μL of aniline, dissolve them in 10 mL of ethanol, react at 80 °C for 24 h, and separate the powder to obtain the aldehyde monomer. Ultrasonically dissolve the aldehyde monomer in 0.5 mL of N,N-dimethylacetamide to prepare an aldehyde monomer solution; ultrasonically dissolve the amine monomer p-phenylenediamine corresponding to the molar ratio of the aldehyde monomer and 20 μL of polyethyleneimine (molecular weight 600) in 0.5 mL of N,N-dimethylacetamide to prepare an amine monomer solution; mix the amine monomer and the aldehyde monomer solution evenly, let it stand for a period of time, cast it on the upper layer of a glass slide, and evaporate the solvent to obtain the amorphous film.

[0023] Step 2: Conversion of the amorphous film to the COF film: Place the amorphous film obtained in Step 1 in a mixed solution with a solvent to catalyst ratio of 6:4, and perform heat treatment at 65 °C for 3 h to obtain the COF-PEI20(3) film.

[0024] The COF-PEI20(3) film obtained in Example 1 was used for nanofiltration separation, and the separation performance was: the pure water flux was 121.76 Lm -2 h -1 bar -1 , the flux of the Congo red solution (concentration 100 ppm) was 115.89 L m -2 h -1 bar -1 , and the retention of Congo red was 98.48%.

[0025] Example 2

[0026] The preparation process is as follows:

[0027] Step 1: Preparation of amorphous film: Weigh 291.85 mg of phloroglucinol trialdehyde and 783.65 μL of aniline, dissolve them in 10 mL of ethanol, react at 80 °C for 24 h, and obtain aldehyde monomers after separating the powder. Ultrasonically dissolve the aldehyde monomers in 0.5 mL of N,N-dimethylacetamide to prepare an aldehyde monomer solution; ultrasonically dissolve p-phenylenediamine, which is the amine monomer corresponding to the molar ratio of the aldehyde monomer, and 30 μL of polyethyleneimine (molecular weight 600) in 0.5 mL of N,N-dimethylacetamide to prepare an amine monomer solution; mix the amine monomer solution and the aldehyde monomer solution evenly, let it stand for a period of time, cast it on the upper layer of a glass slide, and evaporate the solvent to obtain an amorphous film.

[0028] Step 2: Conversion of amorphous film to COF film: Place the amorphous film obtained in Step 1 in a mixed solution with a solvent-to-catalyst ratio of 6:4, and perform heat treatment at 65 °C for 3 h to obtain COF-PEI30(3) film.

[0029] The COF-PEI30(3) film obtained in Example 1 was used for nanofiltration separation. The separation performance was: the pure water flux was 233.81 Lm -2 h -1 bar -1 , the flux of Congo red solution (concentration 100 ppm) was 215.67 L m -2 h -1 bar -1 , and the retention of Congo red was 98.69%.

[0030] Example 3

[0031] The preparation process is as follows:

[0032] Step 1: Preparation of amorphous film: Weigh 291.85 mg of phloroglucinol trialdehyde and 783.65 μL of aniline, dissolve them in 10 mL of ethanol, react at 80 °C for 24 h, and obtain aldehyde monomers after separating the powder. Ultrasonically dissolve the aldehyde monomers in 0.5 mL of N,N-dimethylacetamide to prepare an aldehyde monomer solution; ultrasonically dissolve p-phenylenediamine, which is the amine monomer corresponding to the molar ratio of the aldehyde monomer, and 40 μL of polyethyleneimine (molecular weight 600) in 0.5 mL of N,N-dimethylacetamide to prepare an amine monomer solution; mix the amine monomer solution and the aldehyde monomer solution evenly, let it stand for a period of time, cast it on the upper layer of a glass slide, and evaporate the solvent to obtain an amorphous film.

[0033] Step 2: Conversion of amorphous film to COF film: Place the amorphous film obtained in Step 1 in a mixed solution with a solvent-to-catalyst ratio of 6:4, and perform heat treatment at 65 °C for 3 h to obtain COF-PEI40(3) film.

[0034] The COF-PEI40(3) film obtained in Example 2 was used for nanofiltration separation. The separation performance was: the pure water flux was 344.09 Lm-2 h -1 bar -1 The flux of Congo red solution (concentration 100 ppm) was 291.90 L m -2 h -1 bar -1 and the rejection of Congo red was 99.89%.

[0035] Example 4

[0036] The preparation process is as follows:

[0037] Step 1: Preparation of the amorphous film: Weigh 291.85 mg of phloroglucinol and 783.65 μL of aniline, dissolve them in 10 mL of ethanol, react at 80 °C for 24 h, and separate the powder to obtain the aldehyde monomer. Ultrasonically dissolve the aldehyde monomer in 0.5 mL of N,N-dimethylacetamide to prepare an aldehyde monomer solution; ultrasonically dissolve the amine monomer p-phenylenediamine corresponding to the molar ratio of the aldehyde monomer and 50 μL of polyethyleneimine (molecular weight 600) in 0.5 mL of N,N-dimethylacetamide to prepare an amine monomer solution; mix the amine monomer and the aldehyde monomer solution evenly, let it stand for a period of time, cast it onto the upper layer of a glass slide, and evaporate the solvent to obtain the amorphous film.

[0038] Step 2: Conversion of the amorphous film to a COF film: Place the amorphous film obtained in Step 1 in a mixed solution with a solvent to catalyst ratio of 6:4, and perform heat treatment at 65 °C for 3 h to obtain the COF-PEI50(3) film.

[0039] The COF-PEI50(3) film obtained in Example 3 was used for nanofiltration separation, and the separation performance was: the pure water flux was 405.05 Lm -2 h -1 bar -1 The flux of Congo red solution (concentration 100 ppm) was 353.38 L m -2 h -1 bar -1 and the rejection of Congo red was 98.56%.

[0040] Example 5

[0041] The preparation process is as follows:

[0042] Step 1: Preparation of amorphous film: Weigh 291.85 mg of phloroglucinol and 783.65 μL of aniline, dissolve them in 10 mL of ethanol, react at 80 °C for 24 h, and separate the powder to obtain the aldehyde monomer. Ultrasonically dissolve the aldehyde monomer in 0.5 mL of N,N-dimethylacetamide to prepare the aldehyde monomer solution; ultrasonically dissolve p-phenylenediamine, which is the amine monomer corresponding to the aldehyde monomer in terms of molar ratio, and 40 μL of polyethyleneimine (molecular weight 600) in 0.5 mL of N,N-dimethylacetamide to prepare the amine monomer solution; mix the amine monomer solution and the aldehyde monomer solution evenly, let it stand for a period of time, cast it on the upper layer of a glass slide, and evaporate the solvent to obtain the amorphous film.

[0043] Step 2: Conversion of amorphous film to COF film: Place the amorphous film obtained in Step 1 in a mixed solution with a solvent-to-catalyst ratio of 6:4, and perform heat treatment at 65 °C for 12 h to obtain the COF-PEI40(12) film.

[0044] Use the COF-PEI40(12) film obtained in Example 4 for nanofiltration separation. The separation performance is as follows: the pure water flux is 651.76 Lm -2 h -1 bar -1 , the flux of Congo red solution (concentration 100 ppm) is 567.34 L m -2 h -1 bar -1 , and the retention of Congo red is 88.11%.

[0045]

[0046] Table 1 Nanofiltration performance table of COF film.

Claims

1. A method for rapidly preparing an imine covalent organic framework membrane, characterized in that It includes the following steps: Step 1: Preparation of the amorphous film 1.8 mmol of benzene-1,3,5-tricarbaldehyde and 8.6 mmol of aniline are dissolved in 10 mL of ethanol and reacted at 80 °C for 24 h to prepare the aldehyde monomer BTPA; the aldehyde monomer BTPA is ultrasonically dissolved in N,N-dimethylacetamide to prepare an aldehyde monomer solution, the amine monomer p-phenylenediamine PDA and different amounts of polyethyleneimine PEI are ultrasonically dissolved in N,N-dimethylacetamide to prepare an amine monomer solution, and then the aldehyde monomer solution and the amine monomer solution are mixed and ultrasonically homogenized and left standing for several hours; the mixed monomer solution is cast onto the upper layer of a glass slide, and after solvent evaporation, an amorphous film is obtained; Step 2: Transformation of the amorphous film into a COF film The amorphous film obtained in Step 1 is placed in a mixed solution of a solvent and a catalyst, and heat-treated at 65 °C for a certain time to obtain a COF-PEIa(b) film, where a represents the content of PEI and b represents the heat treatment time.

2. The method for rapidly preparing a covalent organic framework membrane according to claim 1, characterized in that: In Step 1, the molecular weight of PEI is one or several of 600, 800, 1800, 3000, 10000, 30000 or 50000.

3. The method for rapidly preparing a covalent organic framework membrane according to claim 1, wherein: In Step 1, the usage amount of PEI is 10 μL, 20 μL, 30 μL, 40 μL or 50 μL.

4. The method for rapidly preparing a covalent organic framework membrane according to claim 1, wherein: In Step 1, the solvent evaporation time is controlled to be 1 h, 3 h, 6 h, 12 h or 24 h.

5. The method for rapidly preparing a covalent organic framework membrane according to claim 1, wherein: In Step 2, the volume ratio of the solvent to the catalyst used during the heat treatment is 2:8, 4:6, 6:4 or 8:

2.

6. The method for rapidly preparing a covalent organic framework membrane according to claim 1, wherein: In Step 2, the heat treatment time is 1 h, 3 h, 6 h, 12 h or 24 h.

7. Application of the covalent organic framework film prepared by the method according to any one of claims 1-6 in molecular and / or molecular ion separation.

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